This invention relates to a marine stern drive having a through-housings lubrication system. More particularly, the invention involves a stern drive adapted to be mounted externaly of the transom of a boat and which is driven by an inboard engine. The stern drive includes a gimbal housing, bell housing and drive shaft housing which form an assembly for carrying and driving a propeller. The various components of the assembly must be supplied with lubricating fluid therein for the moving parts of the drive, and it is desirable to be able to readily check and fill to the proper level and check the condition of the fluid.
Lubricating systems for submerged driving mechanisms are known. See, for example, U.S. Pat. No. 3,335,817. In that patent, an underwater drive unit has a lubricant chamber 32 therein which is connected through the bottom 10 of a boat and to a clear inspection chamber 85 mounted within the boat and which is connected to the intake manifold of an inboard engine 12.
Another known lubricating system having inspection capabilities within the boat has been in kit form, wherein a special hole was drilled through the transom and a hose passed therethrough and connected the stern drive assembly with a clear inspection container. This required various brackets and fasteners which were not only poor from an aesthetic standpoint, but which were subject to corrosion and other physical damage.
Other lubricant checking systems have included a dip stick disposed in an inboard heavy reservoir cast into the inner transom plate. In other instances, a removable full level plug was disposed in the drive shaft housing, but plug removal for checking required that the boat be removed from the water. It is an object of the present invention to provide a stern drive arrangement having numerous advantages over those of the previously mentioned known devices.
In accordance with the various aspects of the invention, a stern drive unit includes an assemblage of a propeller-carrying drive shaft housing, a bell housing and gimbal housing. Mating flow-thru passages are disposed in the drive shaft housing and bell housing, and a dual control valve system joins the passages at their juncture. The valve system is arranged to be open when the two housings are assembled, but closes automatically when the housings are disassembled to retain lubricant in the separate housing assemblies when the latter are separated for servicing. The valve system includes a valve in one of the passages which is constructed to be snapped together and to be held firmly within the passage, but manually and quickly releasable therefrom when desired.
The fluid passage in the bell housing communicates to the gimbal housing which has a sealed fitting and a lubricant carrying portion passing through the usual gimbal mounting hole of the boat transom. Lubricant thus passes through the various housings themselves, and does not require drilling of special holes in the transom.
An inboard reservoir container connected to the gimbal housing passage permits inspection of the level and condition of the lubricant. The container has a one-way valve therein which prevents outward leakage of lubricant fluid, but which permits sucking back of lubricant into the system during drive cooling.